Electromagnet.



P BOSSU.

ELECTROMAGNET.

APPLICATION FILED DEC. l9, I9I3- 1,242,763. Patented (m. 9, 1917. fly, 11

2 g 2 2 faker/"e T50686 UNITED STATES PATENT OFFICE.

PIERRE IBOSSU, OF PARIS, FRANCE, ASSIGNOR T0 SOCIETE ANONYME DES E'IABLISSE- MENTS I4. BLERIO'I, 0F PARIS, FRANCE.

ELECTROMAGNET.

Original application filed December 14,

To all whom it may concern:

Be it known that I, PIERRE BOSSU, a citizen of the Republic of France, residing at Paris, France, have invented certain new and useful Improvements in Electromagnets, of which the following is a specification.

The present invention relates to improvements in electro-magnets and similar devices having an armature movable relatively thereto, and the object of this invention is to provide means to compensate for the effects of the variations in reluctance occurring in the magnetic field due to the varying distances of the armature from the core of the magnet, a resistance being used, according to the present invention, which is adapted to-be connected in series with the winding of the electro-magnet and the value of whichis so modified as to compensate for the variations in reluctance in every posi tion of the armature, or practically so. The present application is a division of my prior application, Serial No. 736,838, filed December 14, 1912.

To these and other ends, the invention consists in certain improvements, and combinations and arrangements of parts, all as will be hereinafter more fully described, the novel features being pointed out particularly in the claims at the end of the specification.

In the accompanying drawing:

Figure 1 is a view in elevation showing an electro-magnet having the present invention applied thereto;

Fig. 2 is a side elevation of an electromagnet equipped with another embodiment of the invention;

Fig. 3 shows an end elevation of the same.

Similar parts are designated by the same reference characters in the several views.

In each instance shown the electro-ma et embodies a core a, the core illustrat in Figs. 1 and 2 being of horse-shoe formand the cores are provided with windings or coils b to excite them. 0 represents in each instance the armature which is movable toward and from the magnet core. As shown in Fig. 1, the armature c is pivoted at one end on the axis 0, and the opposite or mov-- able end of the armature is connected by a link a to a lever or arm m, the latter being pivoted at m whereby the opposite end 0 Specification of Letters Patent.

Patented Oct. 9, 1917.

1912, Serial No. 736,838. Divided and this application filed December 19, 1913. $6118.11). 807,772- I this lever or arm will swing in an are. This free or movable end of the lever or arm m is provided with a brush m. One side of the circuit is connected to one terminal of the coil or winding 6 while the other side of the circuit is connected to the swinging lever orarm m preferably at the pivot m. A resistance is provided which is adapted to be connected in series with the coil or winding of the electro-magnet.' The resistance d shown in Fig. 1 has a contact portion of arclike or segmental form, and the brush m maintains engagement with this segmental portion of the resistance while the armature occupies a position in contact with the core, the released position shown in Fig. 1, and also any intermediate positions. This resistance d is so calculated that it will compensate for the effects of the variations in reluctance of the magnetic field for all positions of the armature, the value of the resistance being at a minimum or practicall zero when the armature is in fully release position, and the value of the resistance will increase progressively as the armature moves toward contact position, it having a maximum value when the armature reaches contact position. As the armature moves from contact position to released position, the value of the resistance will decrease proportionately until it reaches a minimum or zero value when the armature is in fully released position.

In that embodiment of the invention shown in Figs. 2 and 3, the armature c is pivoted on an axis 0' as before, the armature, however, being shown above the magnet instead of below as in the preceding instance and consequently means is provided for returning the armature to released position when the core of the magnet is deenergized or its magnetism or attractive force falls below a given value, it having a lever 0 which is mounted at an interd, d and d, the terminals of these coils or resistance sections bein connected to con tacts e, e, e and e, t e remaining terminal of the coil or resistance section d being connected to a contact 6 which latter in turn is connected directlyto one side of the circuit. The armature c carries or is operatively connected to a switch which is adapted to control the resistance contacts. This switch in the present instance embodies a. series of switch blades n, n, n, n and n which are of varying, curvatures. These switch blades are all connected in common at their attached ends to the winding of the electro-magnet, the latter being connected to the opposite side of the circuit. When the armature is in contact position as shown in Fi 2 and 3, the switch blades are all out 0 contact with the resistance contacts, except the switch blade n of greatest curvature which is then in engagement with the contact e of the resistance and hence the resistance at this time will have the highest value as the exciting current for the magnet must flow through all the coils of the resistance. As the armature moves in a direction from the contact position and toward released position, the switch blades n, n, n and n of diminishing curvatures will successively engage the resistance contacts e, e, e and e, thereby cutting out of the circuit the resistance coils d, d, d and d and diminishing the value of the resistance until the armature is in fully re leased position at which time the contacts n ance are successively inserted in the magnet circuit by a reverse operation of the switch and thereby the value of the resistance 1s progressively increased until it reaches a maximum when the armature is in contact or attractedposition.

As shownin the drawin a sheet of non magnetic material f is pre erably interposed between the core a and the armature c.

I claim as my invention The combination with an electro-magnet and a relatively movable armature, of resistance divided into a series of coils having individual contacts, and a switch movable by the armature and embodying a series of spring blades of difierent curvatures arranged to coiiperate with respective contacts of the resistance coils whereby the resistance is progressively increased when the armature moves toward contact position and is diminished as the armature moves toward released position to compensate for the effects of variation of reluctance of the magnetic field for all positions of the armature.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

PIERRE BOSSU. Witnesses Hanson C. Con, PAUL Bank. 

